In a mobile ad hoc network (MANET) of nodes, nodes can move independently, which changes the network topology. Communication of packets in a MANET is usually multi-hop, and each node can forward packets for other nodes. However, the transmission power, computational ability and available bandwidth for the node is limited.
Because MANET lacks a structure for autonomous peer nodes, MANET is prone to selfish behaviors and malicious attacks. MANET is inherently insecure and untrustful. Selfish relay nodes can drop packets to reduce their power consumption, and extend battery life. Therefore, selfish behavior should be detected and identified. Packets can also be falsified by relays.
One of the solutions preserves security in MANET by including a reputation system to monitor misbehaving nodes. The reputation of a node is treated as a measure of uncertainty and confidence to evaluate trust in MANET. That scheme uses a modified Bayesian estimation method, or a self-policing reputation mechanism. The scheme is based on local observations at the nodes. The scheme leverages second-hand trust information to rate and detect the misbehaving nodes.
For a large-scale MANET, hierarchical reputation management can be considered, e.g., with combination between reputation and price systems. A distributed hash table approach can be implemented to store reputation records.